Twenty-one people on a senior citizen cruise died yesterday when their sightseeing boat overturned on upstate Lake George.

The victims were Canadian tourists, local officials said.

Forty-six people were aboard the 40-foot Ethan Allen when it was swamped by the wake of a larger, paddle-wheel tour boat and tipped over on its side.

Frank Sause, owner of Cramer’s Point Motel & Cottages, who helped carry bodies and survivors from rescue boats to shore, told The Post:

“Everybody was in complete shock and the captain was really shaken up.

“The boats were bringing the victims in and we were putting the bodies on the beach. It was unreal – seeing the bodies there. There were more and more coming in.

“One man who survived said to me, ‘That’s my wife over there. They just put her on a gurney and she’s dead.’

“I said, ‘Don’t jump to conclusions. She may be OK,’ and he said, ‘No, she’s dead.’ “

Sause recalled, “One guy was giving a victim CPR. I tried to settle people down as best I could – keep them calm.

“The people who survived were all hugging each other and saying to the rescuers, ‘Thank you for being there!’ “

The tragedy took place on a beautiful fall day in the Adirondacks. It was sunny, the lake was calm and the water temperature in the mid-60s.

The boat was 50 to 100 feet off shore, about 10 miles north of Lake George Village. Warren County Sheriff Larry Cleveland said the accident happened so quickly, no one had time to put on a life jacket.

“It was surreal. It was the worst accident I think that’s happened on this lake,” said John Magill, a General Electric retiree who lives near the accident scene. Just dead bodies coming out. There was quite a few.

“Most of them elderly people who couldn’t swim,” said Magill.

He said there were many emergency workers at the scene, several helicopters in the air, and several boaters who rushed to help – but there was little that could be done.

“Either people drowned or people were alive,” Magill said. “There wasn’t anything anyone could do.”

The survivors, he said, “were upset, I think some of them were in shock, or really didn’t know what was going on.”

Those who died were apparently trapped on the boat, which is covered by Plexiglas.

Ed Ratloff, who also runs a nearby motel, said, “It’s a small boat; 40 foot long, no superstructure on it.

“It’s got a covered roof and people sit from the left to the right. It has Plexiglas covering it. So when that thing tipped, the people couldn’t get out.”

The Ethan Allen is owned by Shoreline Cruises of Lake George.

The paddle-wheeler, a 117-foot Mohican, is operated by Lake George Steamboat Co.

Neither company was available to comment yesterday.

A woman at the Fort William Henry Conference Center at Lake George Village said she’d seen the senior citizens on their bus tour earlier in the day.

“They were in the village area earlier, they just seemed like a nice group of people going about visiting the shops and restaurants,” said the woman.